Strains of Vibrio cholerae O1, El Tor resistant to multiple antimicrobial agents, were isolated in Kenya between 1982 and 1985. Strains of serotype Ogawa were resistant to tetracycline, ampicillin, and trimethoprim/sulfamethoxazole. Resistance was mediated in all instances by a plasmid ca 100 mD of incompatibility group C. Based on analysis of restriction endonuclease digests, all Ogawa isolates had an identical resistance plasmid. This plasmid differed from plasmids in resistant V. cholerae O1 strains isolated in Tanzania, Nigeria, and Bangladesh. On Southern blot analysis of restriction endonuclease digests of chromosomal DNA using DNA probes there were no apparent differences between Kenyan V. cholerae O1 strains isolated before and after emergence of antibiotic resistance; however, a majority of El Tor strains isolated in other geographic areas had the same Southern blot pattern. Our data document the apparent endemicity of multiply antimicrobial resistant V. cholerae O1 strains in Kenya, and the persistence of a single unique resistance plasmid among isolates of serotype Ogawa.